1. Field of the Invention
The present invention relates to a transfer medium suitable for use in forming an image on a medium to be transferred (hereinafter referred to as a xe2x80x9ctransfer-printing mediumxe2x80x9d), such as cloth or film, by transfer printing, and more particularly to a transfer medium for ink-jet recording, on the transfer layer of which an image is formed using an ink-jet recording system, and an image forming process using this transfer medium.
2. Related Background Art
An ink-jet recording system is intended to make a record of images, characters and the like by generating and ejecting fine droplets of an ink by any one of various ink ejection systems, for example, an electrostatic attraction system, a system in which a piezoelectric element is used to give an ink mechanical vibration or change, and a system in which an ink is heated to form bubbles in the ink so as to use the pressure thus produced, and applying part or all of the droplets to a recording medium such as paper. The ink-jet recording system attracts attention as a recording system which scarcely produces noise and can conduct high-speed printing and color printing.
In recent years, ink-jet printers, by which full-color printing can be simply conducted as described above, have been spread, and there has thus been an increasing demand for conducting color printing on various media using these printers. In order to meet such a demand, particular attention is paid to printing techniques using a transfer printing system in that printing can be conducted irrespective of the form of recording media, namely, the formation of an image can be performed on any medium which does not permit direct printing by a printer.
Some transfer media making good use of an ink-jet recording system have been proposed to date (for example, Japanese Patent Application Laid-Open No. 8-207426, Japanese Patent Application Laid-Open No. 8-207450, U.S. Pat. No. 5,501,902, etc.).
According to a transfer printing process using such a conventional transfer medium as described above, the desired image is first formed on a transfer layer of the transfer medium in accordance with an ink-jet system. The transfer medium and a transfer-printing medium such as cloth are then laid to overlap each other with the transfer layer, on which the image has been formed, on the side of the transfer-printing medium. In this state, both media are heated from the back side of the transfer medium to transfer the transfer layer to the surface of the transfer-printing medium, thereby forming the image on the transfer-printing medium. Such a transfer printing process is of course conducted industrially and often carried out in the home using a general-purpose household iron.
At this time, in order to successfully conduct the transfer printing, it is necessary to exactly heat the whole surface of the transfer layer. If a support is separated from the transfer layer while unheated portions or insufficiently heated portions are left at the transfer layer, there arises a problem that adhesion at these portions between the transfer layer and the transfer-printing medium such as cloth becomes insufficient, or that a part of the transfer layer remains on the support (for example, release paper), on which the transfer layer is supported, without achieving whole-surface transfer. Such incomplete transfer results in the fact that when the cloth having the incomplete transfer layer is laundered or otherwise rubbed, a part or the whole of the transfer layer is easily separated, or many cracks occur in the transfer layer to impair the quality of the image.
Besides, when the transfer printing is conducted at a low temperature, there arises a problem that adhesion between the transfer layer and the transfer-printing medium such as cloth becomes insufficient, or that a part of the transfer layer remains on the support (for example, release paper), on which the transfer layer is supported, without achieving whole-surface transfer. Such incomplete transfer results in the fact that when the cloth having the incomplete transfer layer is washed or otherwise rubbed, a part or the whole of the transfer layer is easily separated, or many cracks occur in the transfer layer to impair the quality of the image. On the other hand, when the transfer printing is conducted at a too high temperature, dyes which form the image are discolored, or the extreme case is that the cloth may also be discolored. Accordingly, the transfer printing requires to sufficiently heat the transfer layer at an optimum temperature that is not lower than a temperature, at which transfer can take place, but is not too high, in order for the materials, which form the transfer layer, to fully penetrate into interstices of the transfer-printing medium such as cloth throughout the transfer layer, whereby the transfer layer is transferred firmly to the cloth without causing discoloration of the dyes and transfer-printing medium.
In order to meet such requirements in the above-described transfer printing process, no particularly great problem arises in a heating step for transfer printing when the transfer printing using the transfer medium is performed industrially. When the transfer of the transfer layer is conducted by a household iron in the home, however, it is difficult to heat the whole back surface of the support corresponding to the area of the transfer layer even when the heating is conducted considerably carefully, since the area of the transfer layer is generally considerably wider than the area of the heating surface of the iron, and the heating is conducted from the side of the support opposite to the transfer layer. Accordingly, a problem that unheated portions remain in the transfer layer arises. In addition, since it is hard to say that the temperature of the heating surface of the household iron is even as a whole, and the temperature of the heating surface varies with the position, and moreover the temperature cannot be set precisely, even heating may not be performed in some cases even when the whole surface of the transfer layer is ironed, so that insufficiently heated portions remain. When the support is separated from the transfer layer in this state, the transfer layer transferred to the transfer-printing medium tends to separate or cracks to a great extent by washing or other rubbing, as described above.
It is an object of the present invention to provide a transfer medium for ink-jet recording, by which a transfer layer thereof can be easily heated throughout the whole surface thereof in a suitable state to transfer it to a transfer-printing medium such as cloth even when the step of transferring the transfer layer to the transfer-printing medium such as cloth is carried out in the home using a household iron or the like the heating surface of which is considerably narrower than the area of the transfer layer, to say nothing of a case where the step is industrially carried out, and which permits the simple formation of a high-quality image, and an image forming process using this transfer medium.
Another object of the present invention is to provide a transfer medium for ink-jet recording, which permits the simple formation of an image on a printing medium such as cloth, which does not permit direct ink-jet recording, in the home by using a general-purpose ink-jet recording apparatus and household iron without need of any particular apparatus, and the provision of a transferred image having excellent image properties and high fastness properties such as fastness to washing, and an image forming process using this transfer medium.
The above objects can be achieve by the present invention described below.
According to the present invention, there is thus provided a transfer medium for ink-jet recording adapted to form an image on a transfer layer thereof and then heat the transfer layer from the side of a support of the transfer medium to transfer the transfer layer to a transfer-printing medium, wherein an index is provided on the support.
According to the present invention, there is also provided an image forming process comprising the steps of forming an image on the transfer layer of the transfer medium for ink-jet recording described above in accordance with an ink-jet system, laying the transfer medium and a transfer-printing medium to overlap each other with the transfer layer, on which the image has been formed, on the side of the transfer-printing medium, and heating the transfer layer from the side of the support of the transfer medium to transfer the transfer layer of the transfer medium to the surface of the transfer-printing medium, wherein the heating is carried out by utilizing the index provided on the support.
According to the present invention, the index which indicates the position to be heated is provided on the support. Therefore, heat can be fully applied throughout the whole surface of the transfer layer of the transfer medium even when a heating surface upon heating is narrower than the area of the transfer layer and varies in temperature with the position, for example, when the transfer step is carried out in the home using a household iron. As a result, the transfer layer can be simply transferred to a transfer-printing medium such as cloth with satisfactory results.
In particular, when the index provided on the support is provided as a linear index at interlinear intervals of at most a half of the width of the heating surface of the iron, the problem that unheated portions or insufficiently heated portions remain in the transfer layer can be solved, so that the transfer layer of the transfer medium can be transferred to a transfer-printing medium such as cloth with wholly satisfactory results.
Moreover, according to the present invention, when for example, heat-sensitive portions, the visual appreciation of which changes at a temperature somewhat higher than a preferred transfer temperature, are formed as an index on the back surface of the transfer medium, the transfer layer of the transfer medium can be easily transferred to a transfer-printing medium such as cloth in an appropriate state even when transfer printing is carried out in the home using, for example, a household iron that cannot suitably set and control its temperature to a particular temperature.